Lesson Learned About Gripper

Question

If I would not have been so impatient when I built the arm, I would not have had to do it over. I hot melt glued the arm together instead of silicone. And sometimes servos get hot. It melted the glue and Bang!! The whole gripper came apart. Not only that when I touched the servo, the hot melt glue that was melted got on my hand and burn a water blister into my finger!

:(

Troy · Answer

Yikes! Good thing to pass on.

jstarne1 · Answer

Your servo shouldnt be that hot?!

DJ Sures · Answer

That's crazy hot! I use the heavy duty servos in omnibot 2000's arm - which is super heavy. They get warm but not that hot. I have them attached entirely by hot glue. Probably depends on the used also. But you are right, an epoxy will work for ever, like JB Weld. Before applying, scuff the area on the servo that you will glue for a better stick. The servos are a very smooth surface and that's not good for glues. Also wipe the area with rubbing alcohol and let dry before glueing. I find that helps.

MovieMaker · Answer

Thanks for the tips. I think it got in a position that it did not like. I used Goop on it. We will see Monday after the Goop dries. It is possible it is a bad servo. I purchased it years ago from an RC hobby shop. It was the only one I had that came close to fitting the hand from spark-fun. They called for a medium servo and it is a mini. I may be just overworking it. spark fun is out of servos in this category. There must be a World servo problem.

Troy · Answer

@MovieMaker, I think this is the servo according to the datasheet for medium servo listed on Sparkfun. Its a s3317s servo.

MovieMaker · Answer

NO it is a micro or mini that I bought from the RC Hobby shop. i will probably replace the gripper and servo once sparkfun gets the servo in stock. I had a dozen servos and NONE fit. :-( It is just moving the gripper and that should not be very hard to do. But, I Gooped it in place now. So,by Monday, it should be in place enough to work.

Troy · Answer

Yeah that was a different one. Btw I noticed this comment posted by Hobbytronics on that servo. Quote: ------ For those of you having problems with these running hot and drawing excess current, it seems to be because you are trying to drive them beyond the mechanical end stops. If you are driving these servos using the Arduino Servo library (or your own microcontroller code), then the high value of 180 (Arduino), which creates a 2.4ms pulse width, may be too high and tries to drive the servo past its mechanical end stop. This leads to a high current being drawn (1A+) and the servo gets hot. If you reduce the Arduino Sketch value from 180 down to 170 (or drop your pulse width down to 2.3ms max) then you should be ok. In normal operation (no load), these servos only need about 50mA when moving and virtually nothing when stationary. It seems that the setting of the mechanical end stop varies somewhat. -------

MovieMaker · Answer

I felt the servo and manually turned it and I found out it has some bad gears inside. Probably one was stuck. I always put them 10 and 90 except in one case I needed to go to 5. But that is rare.

MovieMaker · Answer

@GlickClick Spark Fun calls it the 10333. If this is the same specs, I would like to order.But, I have tried so many and was the wrong size. Do you think that the specs match?

MovieMaker

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